package com.puff.framework.time;

import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.Serializable;
import java.text.DateFormat;
import java.text.DateFormatSymbols;
import java.text.FieldPosition;
import java.util.ArrayList;
import java.util.Calendar;
import java.util.Date;
import java.util.GregorianCalendar;
import java.util.List;
import java.util.Locale;
import java.util.TimeZone;
import java.util.concurrent.ConcurrentMap;

import com.puff.framework.utils.jdk.ConcurrentHashMapV8;

/**
 * <p>FastDatePrinter is a fast and thread-safe version of
 * {@link java.text.SimpleDateFormat}.</p>
 *
 * <p>This class can be used as a direct replacement to
 * {@code SimpleDateFormat} in most formatting situations.
 * This class is especially useful in multi-threaded server environments.
 * {@code SimpleDateFormat} is not thread-safe in any JDK version,
 * nor will it be as Sun have closed the bug/RFE.
 * </p>
 *
 * <p>Only formatting is supported, but all patterns are compatible with
 * SimpleDateFormat (except time zones and some year patterns - see below).</p>
 *
 * <p>Java 1.4 introduced a new pattern letter, {@code 'Z'}, to represent
 * time zones in RFC822 format (eg. {@code +0800} or {@code -1100}).
 * This pattern letter can be used here (on all JDK versions).</p>
 *
 * <p>In addition, the pattern {@code 'ZZ'} has been made to represent
 * ISO8601 full format time zones (eg. {@code +08:00} or {@code -11:00}).
 * This introduces a minor incompatibility with Java 1.4, but at a gain of
 * useful functionality.</p>
 *
 * <p>Javadoc cites for the year pattern: <i>For formatting, if the number of
 * pattern letters is 2, the year is truncated to 2 digits; otherwise it is
 * interpreted as a number.</i> Starting with Java 1.7 a pattern of 'Y' or
 * 'YYY' will be formatted as '2003', while it was '03' in former Java
 * versions. FastDatePrinter implements the behavior of Java 7.</p>
 *
 * @version $Id: FastDatePrinter.java 1567799 2014-02-12 23:25:58Z sebb $
 * @since 3.2
 */
public class FastDatePrinter implements DatePrinter, Serializable {
	// A lot of the speed in this class comes from caching, but some comes
	// from the special int to StringBuffer conversion.
	//
	// The following produces a padded 2 digit number:
	// buffer.append((char)(value / 10 + '0'));
	// buffer.append((char)(value % 10 + '0'));
	//
	// Note that the fastest append to StringBuffer is a single char (used
	// here).
	// Note that Integer.toString() is not called, the conversion is simply
	// taking the value and adding (mathematically) the ASCII value for '0'.
	// So, don't change this code! It works and is very fast.

	/**
	 * Required for serialization support.
	 *
	 * @see java.io.Serializable
	 */
	private static final long serialVersionUID = 1L;

	/**
	 * FULL locale dependent date or time style.
	 */
	public static final int FULL = DateFormat.FULL;
	/**
	 * LONG locale dependent date or time style.
	 */
	public static final int LONG = DateFormat.LONG;
	/**
	 * MEDIUM locale dependent date or time style.
	 */
	public static final int MEDIUM = DateFormat.MEDIUM;
	/**
	 * SHORT locale dependent date or time style.
	 */
	public static final int SHORT = DateFormat.SHORT;

	/**
	 * The pattern.
	 */
	private final String mPattern;
	/**
	 * The time zone.
	 */
	private final TimeZone mTimeZone;
	/**
	 * The locale.
	 */
	private final Locale mLocale;
	/**
	 * The parsed rules.
	 */
	private transient Rule[] mRules;
	/**
	 * The estimated maximum length.
	 */
	private transient int mMaxLengthEstimate;

	// Constructor
	// -----------------------------------------------------------------------
	/**
	 * <p>Constructs a new FastDatePrinter.</p>
	 *
	 * @param pattern  {@link java.text.SimpleDateFormat} compatible pattern
	 * @param timeZone  non-null time zone to use
	 * @param locale  non-null locale to use
	 * @throws NullPointerException if pattern, timeZone, or locale is null.
	 */
	protected FastDatePrinter(final String pattern, final TimeZone timeZone, final Locale locale) {
		mPattern = pattern;
		mTimeZone = timeZone;
		mLocale = locale;

		init();
	}

	/**
	 * <p>Initializes the instance for first use.</p>
	 */
	private void init() {
		final List<Rule> rulesList = parsePattern();
		mRules = rulesList.toArray(new Rule[rulesList.size()]);

		int len = 0;
		for (int i = mRules.length; --i >= 0;) {
			len += mRules[i].estimateLength();
		}

		mMaxLengthEstimate = len;
	}

	// Parse the pattern
	// -----------------------------------------------------------------------
	/**
	 * <p>Returns a list of Rules given a pattern.</p>
	 *
	 * @return a {@code List} of Rule objects
	 * @throws IllegalArgumentException if pattern is invalid
	 */
	protected List<Rule> parsePattern() {
		final DateFormatSymbols symbols = new DateFormatSymbols(mLocale);
		final List<Rule> rules = new ArrayList<Rule>();

		final String[] ERAs = symbols.getEras();
		final String[] months = symbols.getMonths();
		final String[] shortMonths = symbols.getShortMonths();
		final String[] weekdays = symbols.getWeekdays();
		final String[] shortWeekdays = symbols.getShortWeekdays();
		final String[] AmPmStrings = symbols.getAmPmStrings();

		final int length = mPattern.length();
		final int[] indexRef = new int[1];

		for (int i = 0; i < length; i++) {
			indexRef[0] = i;
			final String token = parseToken(mPattern, indexRef);
			i = indexRef[0];

			final int tokenLen = token.length();
			if (tokenLen == 0) {
				break;
			}

			Rule rule;
			final char c = token.charAt(0);

			switch (c) {
			case 'G': // era designator (text)
				rule = new TextField(Calendar.ERA, ERAs);
				break;
			case 'y': // year (number)
				if (tokenLen == 2) {
					rule = TwoDigitYearField.INSTANCE;
				} else {
					rule = selectNumberRule(Calendar.YEAR, tokenLen < 4 ? 4 : tokenLen);
				}
				break;
			case 'M': // month in year (text and number)
				if (tokenLen >= 4) {
					rule = new TextField(Calendar.MONTH, months);
				} else if (tokenLen == 3) {
					rule = new TextField(Calendar.MONTH, shortMonths);
				} else if (tokenLen == 2) {
					rule = TwoDigitMonthField.INSTANCE;
				} else {
					rule = UnpaddedMonthField.INSTANCE;
				}
				break;
			case 'd': // day in month (number)
				rule = selectNumberRule(Calendar.DAY_OF_MONTH, tokenLen);
				break;
			case 'h': // hour in am/pm (number, 1..12)
				rule = new TwelveHourField(selectNumberRule(Calendar.HOUR, tokenLen));
				break;
			case 'H': // hour in day (number, 0..23)
				rule = selectNumberRule(Calendar.HOUR_OF_DAY, tokenLen);
				break;
			case 'm': // minute in hour (number)
				rule = selectNumberRule(Calendar.MINUTE, tokenLen);
				break;
			case 's': // second in minute (number)
				rule = selectNumberRule(Calendar.SECOND, tokenLen);
				break;
			case 'S': // millisecond (number)
				rule = selectNumberRule(Calendar.MILLISECOND, tokenLen);
				break;
			case 'E': // day in week (text)
				rule = new TextField(Calendar.DAY_OF_WEEK, tokenLen < 4 ? shortWeekdays : weekdays);
				break;
			case 'D': // day in year (number)
				rule = selectNumberRule(Calendar.DAY_OF_YEAR, tokenLen);
				break;
			case 'F': // day of week in month (number)
				rule = selectNumberRule(Calendar.DAY_OF_WEEK_IN_MONTH, tokenLen);
				break;
			case 'w': // week in year (number)
				rule = selectNumberRule(Calendar.WEEK_OF_YEAR, tokenLen);
				break;
			case 'W': // week in month (number)
				rule = selectNumberRule(Calendar.WEEK_OF_MONTH, tokenLen);
				break;
			case 'a': // am/pm marker (text)
				rule = new TextField(Calendar.AM_PM, AmPmStrings);
				break;
			case 'k': // hour in day (1..24)
				rule = new TwentyFourHourField(selectNumberRule(Calendar.HOUR_OF_DAY, tokenLen));
				break;
			case 'K': // hour in am/pm (0..11)
				rule = selectNumberRule(Calendar.HOUR, tokenLen);
				break;
			case 'z': // time zone (text)
				if (tokenLen >= 4) {
					rule = new TimeZoneNameRule(mTimeZone, mLocale, TimeZone.LONG);
				} else {
					rule = new TimeZoneNameRule(mTimeZone, mLocale, TimeZone.SHORT);
				}
				break;
			case 'Z': // time zone (value)
				if (tokenLen == 1) {
					rule = TimeZoneNumberRule.INSTANCE_NO_COLON;
				} else {
					rule = TimeZoneNumberRule.INSTANCE_COLON;
				}
				break;
			case '\'': // literal text
				final String sub = token.substring(1);
				if (sub.length() == 1) {
					rule = new CharacterLiteral(sub.charAt(0));
				} else {
					rule = new StringLiteral(sub);
				}
				break;
			default:
				throw new IllegalArgumentException("Illegal pattern component: " + token);
			}

			rules.add(rule);
		}

		return rules;
	}

	/**
	 * <p>Performs the parsing of tokens.</p>
	 *
	 * @param pattern  the pattern
	 * @param indexRef  index references
	 * @return parsed token
	 */
	protected String parseToken(final String pattern, final int[] indexRef) {
		final StringBuffer buf = new StringBuffer();

		int i = indexRef[0];
		final int length = pattern.length();

		char c = pattern.charAt(i);
		if (c >= 'A' && c <= 'Z' || c >= 'a' && c <= 'z') {
			// Scan a run of the same character, which indicates a time
			// pattern.
			buf.append(c);

			while (i + 1 < length) {
				final char peek = pattern.charAt(i + 1);
				if (peek == c) {
					buf.append(c);
					i++;
				} else {
					break;
				}
			}
		} else {
			// This will identify token as text.
			buf.append('\'');

			boolean inLiteral = false;

			for (; i < length; i++) {
				c = pattern.charAt(i);

				if (c == '\'') {
					if (i + 1 < length && pattern.charAt(i + 1) == '\'') {
						// '' is treated as escaped '
						i++;
						buf.append(c);
					} else {
						inLiteral = !inLiteral;
					}
				} else if (!inLiteral && (c >= 'A' && c <= 'Z' || c >= 'a' && c <= 'z')) {
					i--;
					break;
				} else {
					buf.append(c);
				}
			}
		}

		indexRef[0] = i;
		return buf.toString();
	}

	/**
	 * <p>Gets an appropriate rule for the padding required.</p>
	 *
	 * @param field  the field to get a rule for
	 * @param padding  the padding required
	 * @return a new rule with the correct padding
	 */
	protected NumberRule selectNumberRule(final int field, final int padding) {
		switch (padding) {
		case 1:
			return new UnpaddedNumberField(field);
		case 2:
			return new TwoDigitNumberField(field);
		default:
			return new PaddedNumberField(field, padding);
		}
	}

	// Format methods
	// -----------------------------------------------------------------------
	/**
	 * <p>Formats a {@code Date}, {@code Calendar} or
	 * {@code Long} (milliseconds) object.</p>
	 *
	 * @param obj  the object to format
	 * @param toAppendTo  the buffer to append to
	 * @param pos  the position - ignored
	 * @return the buffer passed in
	 */
	@Override
	public StringBuffer format(final Object obj, final StringBuffer toAppendTo, final FieldPosition pos) {
		if (obj instanceof Date) {
			return format((Date) obj, toAppendTo);
		} else if (obj instanceof Calendar) {
			return format((Calendar) obj, toAppendTo);
		} else if (obj instanceof Long) {
			return format(((Long) obj).longValue(), toAppendTo);
		} else {
			throw new IllegalArgumentException("Unknown class: " + (obj == null ? "<null>" : obj.getClass().getName()));
		}
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see org.apache.commons.lang3.time.DatePrinter#format(long)
	 */
	@Override
	public String format(final long millis) {
		final Calendar c = newCalendar(); // hard code GregorianCalendar
		c.setTimeInMillis(millis);
		return applyRulesToString(c);
	}

	/**
	 * Creates a String representation of the given Calendar by applying the rules of this printer to it.
	 * @param c the Calender to apply the rules to.
	 * @return a String representation of the given Calendar.
	 */
	private String applyRulesToString(final Calendar c) {
		return applyRules(c, new StringBuffer(mMaxLengthEstimate)).toString();
	}

	/**
	 * Creation method for ne calender instances.
	 * @return a new Calendar instance.
	 */
	private GregorianCalendar newCalendar() {
		// hard code GregorianCalendar
		return new GregorianCalendar(mTimeZone, mLocale);
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see org.apache.commons.lang3.time.DatePrinter#format(java.util.Date)
	 */
	@Override
	public String format(final Date date) {
		final Calendar c = newCalendar(); // hard code GregorianCalendar
		c.setTime(date);
		return applyRulesToString(c);
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see org.apache.commons.lang3.time.DatePrinter#format(java.util.Calendar)
	 */
	@Override
	public String format(final Calendar calendar) {
		return format(calendar, new StringBuffer(mMaxLengthEstimate)).toString();
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see org.apache.commons.lang3.time.DatePrinter#format(long,
	 * java.lang.StringBuffer)
	 */
	@Override
	public StringBuffer format(final long millis, final StringBuffer buf) {
		return format(new Date(millis), buf);
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see org.apache.commons.lang3.time.DatePrinter#format(java.util.Date,
	 * java.lang.StringBuffer)
	 */
	@Override
	public StringBuffer format(final Date date, final StringBuffer buf) {
		final Calendar c = newCalendar(); // hard code GregorianCalendar
		c.setTime(date);
		return applyRules(c, buf);
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see org.apache.commons.lang3.time.DatePrinter#format(java.util.Calendar,
	 * java.lang.StringBuffer)
	 */
	@Override
	public StringBuffer format(final Calendar calendar, final StringBuffer buf) {
		return applyRules(calendar, buf);
	}

	/**
	 * <p>Performs the formatting by applying the rules to the
	 * specified calendar.</p>
	 *
	 * @param calendar  the calendar to format
	 * @param buf  the buffer to format into
	 * @return the specified string buffer
	 */
	protected StringBuffer applyRules(final Calendar calendar, final StringBuffer buf) {
		for (final Rule rule : mRules) {
			rule.appendTo(buf, calendar);
		}
		return buf;
	}

	// Accessors
	// -----------------------------------------------------------------------
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.apache.commons.lang3.time.DatePrinter#getPattern()
	 */
	@Override
	public String getPattern() {
		return mPattern;
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see org.apache.commons.lang3.time.DatePrinter#getTimeZone()
	 */
	@Override
	public TimeZone getTimeZone() {
		return mTimeZone;
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see org.apache.commons.lang3.time.DatePrinter#getLocale()
	 */
	@Override
	public Locale getLocale() {
		return mLocale;
	}

	/**
	 * <p>Gets an estimate for the maximum string length that the
	 * formatter will produce.</p>
	 *
	 * <p>The actual formatted length will almost always be less than or
	 * equal to this amount.</p>
	 *
	 * @return the maximum formatted length
	 */
	public int getMaxLengthEstimate() {
		return mMaxLengthEstimate;
	}

	// Basics
	// -----------------------------------------------------------------------
	/**
	 * <p>Compares two objects for equality.</p>
	 *
	 * @param obj  the object to compare to
	 * @return {@code true} if equal
	 */
	@Override
	public boolean equals(final Object obj) {
		if (obj instanceof FastDatePrinter == false) {
			return false;
		}
		final FastDatePrinter other = (FastDatePrinter) obj;
		return mPattern.equals(other.mPattern) && mTimeZone.equals(other.mTimeZone) && mLocale.equals(other.mLocale);
	}

	/**
	 * <p>Returns a hashcode compatible with equals.</p>
	 *
	 * @return a hashcode compatible with equals
	 */
	@Override
	public int hashCode() {
		return mPattern.hashCode() + 13 * (mTimeZone.hashCode() + 13 * mLocale.hashCode());
	}

	/**
	 * <p>Gets a debugging string version of this formatter.</p>
	 *
	 * @return a debugging string
	 */
	@Override
	public String toString() {
		return "FastDatePrinter[" + mPattern + "," + mLocale + "," + mTimeZone.getID() + "]";
	}

	// Serializing
	// -----------------------------------------------------------------------
	/**
	 * Create the object after serialization. This implementation reinitializes the
	 * transient properties.
	 *
	 * @param in ObjectInputStream from which the object is being deserialized.
	 * @throws IOException if there is an IO issue.
	 * @throws ClassNotFoundException if a class cannot be found.
	 */
	private void readObject(final ObjectInputStream in) throws IOException, ClassNotFoundException {
		in.defaultReadObject();
		init();
	}

	// Rules
	// -----------------------------------------------------------------------
	/**
	 * <p>Inner class defining a rule.</p>
	 */
	private interface Rule {
		/**
		 * Returns the estimated lentgh of the result.
		 *
		 * @return the estimated length
		 */
		int estimateLength();

		/**
		 * Appends the value of the specified calendar to the output buffer based on the rule implementation.
		 *
		 * @param buffer the output buffer
		 * @param calendar calendar to be appended
		 */
		void appendTo(StringBuffer buffer, Calendar calendar);
	}

	/**
	 * <p>Inner class defining a numeric rule.</p>
	 */
	private interface NumberRule extends Rule {
		/**
		 * Appends the specified value to the output buffer based on the rule implementation.
		 *
		 * @param buffer the output buffer
		 * @param value the value to be appended
		 */
		void appendTo(StringBuffer buffer, int value);
	}

	/**
	 * <p>Inner class to output a constant single character.</p>
	 */
	private static class CharacterLiteral implements Rule {
		private final char mValue;

		/**
		 * Constructs a new instance of {@code CharacterLiteral}
		 * to hold the specified value.
		 *
		 * @param value the character literal
		 */
		CharacterLiteral(final char value) {
			mValue = value;
		}

		/**
		 * {@inheritDoc}
		 */
		@Override
		public int estimateLength() {
			return 1;
		}

		/**
		 * {@inheritDoc}
		 */
		@Override
		public void appendTo(final StringBuffer buffer, final Calendar calendar) {
			buffer.append(mValue);
		}
	}

	/**
	 * <p>Inner class to output a constant string.</p>
	 */
	private static class StringLiteral implements Rule {
		private final String mValue;

		/**
		 * Constructs a new instance of {@code StringLiteral}
		 * to hold the specified value.
		 *
		 * @param value the string literal
		 */
		StringLiteral(final String value) {
			mValue = value;
		}

		/**
		 * {@inheritDoc}
		 */
		@Override
		public int estimateLength() {
			return mValue.length();
		}

		/**
		 * {@inheritDoc}
		 */
		@Override
		public void appendTo(final StringBuffer buffer, final Calendar calendar) {
			buffer.append(mValue);
		}
	}

	/**
	 * <p>Inner class to output one of a set of values.</p>
	 */
	private static class TextField implements Rule {
		private final int mField;
		private final String[] mValues;

		/**
		 * Constructs an instance of {@code TextField}
		 * with the specified field and values.
		 *
		 * @param field the field
		 * @param values the field values
		 */
		TextField(final int field, final String[] values) {
			mField = field;
			mValues = values;
		}

		/**
		 * {@inheritDoc}
		 */
		@Override
		public int estimateLength() {
			int max = 0;
			for (int i = mValues.length; --i >= 0;) {
				final int len = mValues[i].length();
				if (len > max) {
					max = len;
				}
			}
			return max;
		}

		/**
		 * {@inheritDoc}
		 */
		@Override
		public void appendTo(final StringBuffer buffer, final Calendar calendar) {
			buffer.append(mValues[calendar.get(mField)]);
		}
	}

	/**
	 * <p>Inner class to output an unpadded number.</p>
	 */
	private static class UnpaddedNumberField implements NumberRule {
		private final int mField;

		/**
		 * Constructs an instance of {@code UnpadedNumberField} with the specified field.
		 *
		 * @param field the field
		 */
		UnpaddedNumberField(final int field) {
			mField = field;
		}

		/**
		 * {@inheritDoc}
		 */
		@Override
		public int estimateLength() {
			return 4;
		}

		/**
		 * {@inheritDoc}
		 */
		@Override
		public void appendTo(final StringBuffer buffer, final Calendar calendar) {
			appendTo(buffer, calendar.get(mField));
		}

		/**
		 * {@inheritDoc}
		 */
		@Override
		public final void appendTo(final StringBuffer buffer, final int value) {
			if (value < 10) {
				buffer.append((char) (value + '0'));
			} else if (value < 100) {
				buffer.append((char) (value / 10 + '0'));
				buffer.append((char) (value % 10 + '0'));
			} else {
				buffer.append(Integer.toString(value));
			}
		}
	}

	/**
	 * <p>Inner class to output an unpadded month.</p>
	 */
	private static class UnpaddedMonthField implements NumberRule {
		static final UnpaddedMonthField INSTANCE = new UnpaddedMonthField();

		/**
		 * Constructs an instance of {@code UnpaddedMonthField}.
		 *
		 */
		UnpaddedMonthField() {
			super();
		}

		/**
		 * {@inheritDoc}
		 */
		@Override
		public int estimateLength() {
			return 2;
		}

		/**
		 * {@inheritDoc}
		 */
		@Override
		public void appendTo(final StringBuffer buffer, final Calendar calendar) {
			appendTo(buffer, calendar.get(Calendar.MONTH) + 1);
		}

		/**
		 * {@inheritDoc}
		 */
		@Override
		public final void appendTo(final StringBuffer buffer, final int value) {
			if (value < 10) {
				buffer.append((char) (value + '0'));
			} else {
				buffer.append((char) (value / 10 + '0'));
				buffer.append((char) (value % 10 + '0'));
			}
		}
	}

	/**
	 * <p>Inner class to output a padded number.</p>
	 */
	private static class PaddedNumberField implements NumberRule {
		private final int mField;
		private final int mSize;

		/**
		 * Constructs an instance of {@code PaddedNumberField}.
		 *
		 * @param field the field
		 * @param size size of the output field
		 */
		PaddedNumberField(final int field, final int size) {
			if (size < 3) {
				// Should use UnpaddedNumberField or TwoDigitNumberField.
				throw new IllegalArgumentException();
			}
			mField = field;
			mSize = size;
		}

		/**
		 * {@inheritDoc}
		 */
		@Override
		public int estimateLength() {
			return 4;
		}

		/**
		 * {@inheritDoc}
		 */
		@Override
		public void appendTo(final StringBuffer buffer, final Calendar calendar) {
			appendTo(buffer, calendar.get(mField));
		}

		/**
		 * {@inheritDoc}
		 */
		@Override
		public final void appendTo(final StringBuffer buffer, final int value) {
			if (value < 100) {
				for (int i = mSize; --i >= 2;) {
					buffer.append('0');
				}
				buffer.append((char) (value / 10 + '0'));
				buffer.append((char) (value % 10 + '0'));
			} else {
				int digits;
				if (value < 1000) {
					digits = 3;
				} else {
					if (value <= -1) {
						throw new IllegalArgumentException(String.format("Negative values should not be possible", Long.valueOf(value)));
					}
					digits = Integer.toString(value).length();
				}
				for (int i = mSize; --i >= digits;) {
					buffer.append('0');
				}
				buffer.append(Integer.toString(value));
			}
		}
	}

	/**
	 * <p>Inner class to output a two digit number.</p>
	 */
	private static class TwoDigitNumberField implements NumberRule {
		private final int mField;

		/**
		 * Constructs an instance of {@code TwoDigitNumberField} with the specified field.
		 *
		 * @param field the field
		 */
		TwoDigitNumberField(final int field) {
			mField = field;
		}

		/**
		 * {@inheritDoc}
		 */
		@Override
		public int estimateLength() {
			return 2;
		}

		/**
		 * {@inheritDoc}
		 */
		@Override
		public void appendTo(final StringBuffer buffer, final Calendar calendar) {
			appendTo(buffer, calendar.get(mField));
		}

		/**
		 * {@inheritDoc}
		 */
		@Override
		public final void appendTo(final StringBuffer buffer, final int value) {
			if (value < 100) {
				buffer.append((char) (value / 10 + '0'));
				buffer.append((char) (value % 10 + '0'));
			} else {
				buffer.append(Integer.toString(value));
			}
		}
	}

	/**
	 * <p>Inner class to output a two digit year.</p>
	 */
	private static class TwoDigitYearField implements NumberRule {
		static final TwoDigitYearField INSTANCE = new TwoDigitYearField();

		/**
		 * Constructs an instance of {@code TwoDigitYearField}.
		 */
		TwoDigitYearField() {
			super();
		}

		/**
		 * {@inheritDoc}
		 */
		@Override
		public int estimateLength() {
			return 2;
		}

		/**
		 * {@inheritDoc}
		 */
		@Override
		public void appendTo(final StringBuffer buffer, final Calendar calendar) {
			appendTo(buffer, calendar.get(Calendar.YEAR) % 100);
		}

		/**
		 * {@inheritDoc}
		 */
		@Override
		public final void appendTo(final StringBuffer buffer, final int value) {
			buffer.append((char) (value / 10 + '0'));
			buffer.append((char) (value % 10 + '0'));
		}
	}

	/**
	 * <p>Inner class to output a two digit month.</p>
	 */
	private static class TwoDigitMonthField implements NumberRule {
		static final TwoDigitMonthField INSTANCE = new TwoDigitMonthField();

		/**
		 * Constructs an instance of {@code TwoDigitMonthField}.
		 */
		TwoDigitMonthField() {
			super();
		}

		/**
		 * {@inheritDoc}
		 */
		@Override
		public int estimateLength() {
			return 2;
		}

		/**
		 * {@inheritDoc}
		 */
		@Override
		public void appendTo(final StringBuffer buffer, final Calendar calendar) {
			appendTo(buffer, calendar.get(Calendar.MONTH) + 1);
		}

		/**
		 * {@inheritDoc}
		 */
		@Override
		public final void appendTo(final StringBuffer buffer, final int value) {
			buffer.append((char) (value / 10 + '0'));
			buffer.append((char) (value % 10 + '0'));
		}
	}

	/**
	 * <p>Inner class to output the twelve hour field.</p>
	 */
	private static class TwelveHourField implements NumberRule {
		private final NumberRule mRule;

		/**
		 * Constructs an instance of {@code TwelveHourField} with the specified
		 * {@code NumberRule}.
		 *
		 * @param rule the rule
		 */
		TwelveHourField(final NumberRule rule) {
			mRule = rule;
		}

		/**
		 * {@inheritDoc}
		 */
		@Override
		public int estimateLength() {
			return mRule.estimateLength();
		}

		/**
		 * {@inheritDoc}
		 */
		@Override
		public void appendTo(final StringBuffer buffer, final Calendar calendar) {
			int value = calendar.get(Calendar.HOUR);
			if (value == 0) {
				value = calendar.getLeastMaximum(Calendar.HOUR) + 1;
			}
			mRule.appendTo(buffer, value);
		}

		/**
		 * {@inheritDoc}
		 */
		@Override
		public void appendTo(final StringBuffer buffer, final int value) {
			mRule.appendTo(buffer, value);
		}
	}

	/**
	 * <p>Inner class to output the twenty four hour field.</p>
	 */
	private static class TwentyFourHourField implements NumberRule {
		private final NumberRule mRule;

		/**
		 * Constructs an instance of {@code TwentyFourHourField} with the specified
		 * {@code NumberRule}.
		 *
		 * @param rule the rule
		 */
		TwentyFourHourField(final NumberRule rule) {
			mRule = rule;
		}

		/**
		 * {@inheritDoc}
		 */
		@Override
		public int estimateLength() {
			return mRule.estimateLength();
		}

		/**
		 * {@inheritDoc}
		 */
		@Override
		public void appendTo(final StringBuffer buffer, final Calendar calendar) {
			int value = calendar.get(Calendar.HOUR_OF_DAY);
			if (value == 0) {
				value = calendar.getMaximum(Calendar.HOUR_OF_DAY) + 1;
			}
			mRule.appendTo(buffer, value);
		}

		/**
		 * {@inheritDoc}
		 */
		@Override
		public void appendTo(final StringBuffer buffer, final int value) {
			mRule.appendTo(buffer, value);
		}
	}

	// -----------------------------------------------------------------------

	private static final ConcurrentMap<TimeZoneDisplayKey, String> cTimeZoneDisplayCache = new ConcurrentHashMapV8<TimeZoneDisplayKey, String>(7);

	/**
	 * <p>Gets the time zone display name, using a cache for performance.</p>
	 *
	 * @param tz  the zone to query
	 * @param daylight  true if daylight savings
	 * @param style  the style to use {@code TimeZone.LONG} or {@code TimeZone.SHORT}
	 * @param locale  the locale to use
	 * @return the textual name of the time zone
	 */
	static String getTimeZoneDisplay(final TimeZone tz, final boolean daylight, final int style, final Locale locale) {
		final TimeZoneDisplayKey key = new TimeZoneDisplayKey(tz, daylight, style, locale);
		String value = cTimeZoneDisplayCache.get(key);
		if (value == null) {
			// This is a very slow call, so cache the results.
			value = tz.getDisplayName(daylight, style, locale);
			final String prior = cTimeZoneDisplayCache.putIfAbsent(key, value);
			if (prior != null) {
				value = prior;
			}
		}
		return value;
	}

	/**
	 * <p>Inner class to output a time zone name.</p>
	 */
	private static class TimeZoneNameRule implements Rule {
		private final Locale mLocale;
		private final int mStyle;
		private final String mStandard;
		private final String mDaylight;

		/**
		 * Constructs an instance of {@code TimeZoneNameRule} with the specified properties.
		 *
		 * @param timeZone the time zone
		 * @param locale the locale
		 * @param style the style
		 */
		TimeZoneNameRule(final TimeZone timeZone, final Locale locale, final int style) {
			mLocale = locale;
			mStyle = style;

			mStandard = getTimeZoneDisplay(timeZone, false, style, locale);
			mDaylight = getTimeZoneDisplay(timeZone, true, style, locale);
		}

		/**
		 * {@inheritDoc}
		 */
		@Override
		public int estimateLength() {
			// We have no access to the Calendar object that will be passed to
			// appendTo so base estimate on the TimeZone passed to the
			// constructor
			return Math.max(mStandard.length(), mDaylight.length());
		}

		/**
		 * {@inheritDoc}
		 */
		@Override
		public void appendTo(final StringBuffer buffer, final Calendar calendar) {
			final TimeZone zone = calendar.getTimeZone();
			if (zone.useDaylightTime() && calendar.get(Calendar.DST_OFFSET) != 0) {
				buffer.append(getTimeZoneDisplay(zone, true, mStyle, mLocale));
			} else {
				buffer.append(getTimeZoneDisplay(zone, false, mStyle, mLocale));
			}
		}
	}

	/**
	 * <p>Inner class to output a time zone as a number {@code +/-HHMM}
	 * or {@code +/-HH:MM}.</p>
	 */
	private static class TimeZoneNumberRule implements Rule {
		static final TimeZoneNumberRule INSTANCE_COLON = new TimeZoneNumberRule(true);
		static final TimeZoneNumberRule INSTANCE_NO_COLON = new TimeZoneNumberRule(false);

		final boolean mColon;

		/**
		 * Constructs an instance of {@code TimeZoneNumberRule} with the specified properties.
		 *
		 * @param colon add colon between HH and MM in the output if {@code true}
		 */
		TimeZoneNumberRule(final boolean colon) {
			mColon = colon;
		}

		/**
		 * {@inheritDoc}
		 */
		@Override
		public int estimateLength() {
			return 5;
		}

		/**
		 * {@inheritDoc}
		 */
		@Override
		public void appendTo(final StringBuffer buffer, final Calendar calendar) {
			int offset = calendar.get(Calendar.ZONE_OFFSET) + calendar.get(Calendar.DST_OFFSET);

			if (offset < 0) {
				buffer.append('-');
				offset = -offset;
			} else {
				buffer.append('+');
			}

			final int hours = offset / (60 * 60 * 1000);
			buffer.append((char) (hours / 10 + '0'));
			buffer.append((char) (hours % 10 + '0'));

			if (mColon) {
				buffer.append(':');
			}

			final int minutes = offset / (60 * 1000) - 60 * hours;
			buffer.append((char) (minutes / 10 + '0'));
			buffer.append((char) (minutes % 10 + '0'));
		}
	}

	// ----------------------------------------------------------------------
	/**
	 * <p>Inner class that acts as a compound key for time zone names.</p>
	 */
	private static class TimeZoneDisplayKey {
		private final TimeZone mTimeZone;
		private final int mStyle;
		private final Locale mLocale;

		/**
		 * Constructs an instance of {@code TimeZoneDisplayKey} with the specified properties.
		 *
		 * @param timeZone the time zone
		 * @param daylight adjust the style for daylight saving time if {@code true}
		 * @param style the timezone style
		 * @param locale the timezone locale
		 */
		TimeZoneDisplayKey(final TimeZone timeZone, final boolean daylight, final int style, final Locale locale) {
			mTimeZone = timeZone;
			if (daylight) {
				mStyle = style | 0x80000000;
			} else {
				mStyle = style;
			}
			mLocale = locale;
		}

		/**
		 * {@inheritDoc}
		 */
		@Override
		public int hashCode() {
			return (mStyle * 31 + mLocale.hashCode()) * 31 + mTimeZone.hashCode();
		}

		/**
		 * {@inheritDoc}
		 */
		@Override
		public boolean equals(final Object obj) {
			if (this == obj) {
				return true;
			}
			if (obj instanceof TimeZoneDisplayKey) {
				final TimeZoneDisplayKey other = (TimeZoneDisplayKey) obj;
				return mTimeZone.equals(other.mTimeZone) && mStyle == other.mStyle && mLocale.equals(other.mLocale);
			}
			return false;
		}
	}
}
